Despite the recent rash of space-debris problems, the risk that the space shuttle mission to service the Hubble Space Telescope will have a catastrophic collision with space junk and micrometeoroids won’t exceed NASA guidelines.
More precise observations of the orbital debris encircling Earth also showed the amount of junk was slightly lower than had previously been calculated. The new information means the shuttle mission to the Hubble can fly without any safety reservations.
Scientists have found life in an ecosystem trapped underneath a glacier in Antarctica for nearly 2 million years. The microbes, they suggest, are surviving the dark, oxygen-free waters by drawing energy from sulfur and iron. The findings provide insight into how life may have survived “Snowball Earth”–periods when some scientists speculate that the planet was entombed in ice–and hint at the possibility of life in other inhospitable environments, such as Mars and Jupiter’s icy moon Europa.Researchers have found microbial life surviving in the most unusual places: the depths of cold and dark oceans, seething geothermal vents, and the deepest layers of permafrost. And ever since scientists discovered Antarctica’s dark and mysterious subglacial lakes in the late 1960s and early 1970s, they’ve wondered if microbes could make a life for themselves there too. But the challenges of drilling through kilometers of ice and concerns about contaminating these pristine lakes have curtailed previous efforts to find out.
Blood Falls, a small, saltwater outflow from Taylor Glacier’s subglacial lake in Antarctica’s Dry Valleys, offers an alternative. The lake sits beneath 400 meters of ice and trickles out at the glacier’s end, painting an orange stain across the ice as its iron-rich waters rust upon contact with air. The subglacial lake was originally part of a marine fjord system that became trapped as Taylor Glacier enclosed it between 1.5 million and 2 million years ago. Its sporadic outflow allows researchers to explore the lake without drilling or risking contamination of the isolated environment.
Geomicrobiologist Jill Mikucki, now at Dartmouth College, collected water samples from Blood Falls over 6 years. A battery of tests revealed that its waters contained almost no oxygen and hosted a community of at least 17 different types of microorganisms. But how could they have survived for so long, with no light or oxygen? Mikucki and her team uncovered three main clues. First, a genetic analysis of the microbes showed that they were closely related to other microorganisms that use sulfate instead of oxygen for respiration. Second, isotopic analysis of sulfate’s oxygen molecules revealed that the microbes were modifying sulfate in some form but not using it directly for respiration. Third, the water was enriched with soluble ferrous iron, which would happen only if the organisms had converted ferric iron, which is insoluble, to the soluble ferrous form. The best explanation, the team reports in tomorrow’s issue of Science, is that the organisms use sulfate as a catalyst to “breathe” with ferric iron and metabolize the limited amounts of organic matter trapped with them years ago. Lab experiments have suggested this might be possible, but it has never been observed in a natural environment.
The world’s forests are at risk of becoming a source of planet-warming emissions instead of soaking them up like a sponge unless greenhouse gases are controlled, scientists said.
Deforestation emits 20 percent of the world’s carbon dioxide when people cut and burn trees, but standing forests soak up 25 percent of the emissions.
If the Earth heats up 2.5 degrees Celsius (4.5 degrees F) or more, evaporation from the additional heat would lead to severe droughts and heat waves that could kill wide swaths of trees in the tropics of Africa, southern Asia and South America. And emissions from the rotting trees would make forests a source of global warming.
Biomass power – such as burning wood for energy – could do more harm than good in the battle to reduce greenhouse gases, UK’s Environment Agency warns. Ploughing up pasture to plant energy crops could produce more CO2 by 2030 than burning fossil fuels, if not done in a sustainable way, it said. Its study found waste wood and MDF produced the lowest emissions, unlike willow, poplar and oil seed rape.
